Don Bowey wrote:> On 4/25/06 12:14 AM, in article e2ki8j$cuh$1@home.itg.ti.com, "Steve > Underwood" <steveu@dis.org> wrote: > > >>Joerg wrote: >> >>>Hello Jim, >>> >>> >>>>1200 baud FSK changes frequency in a _single_ cycle, so period-type >>>>demodulation goes to crap quickly in the presence of noise. >>>> >>> >>>Zero-crossers are pretty much a thing of the past here, just like they >>>are for medical ultrasound Doppler. You can do it in the digital domain >>>these days. All it takes is a good uC such as the MSP430. But not a >>>version with a puny 10 or 12 bit converter. They offer some that convert >>>to 16 bits. >> >>What's wrong with a 12 bit converter? The entire telephone network uses >>12 bits. >> >>Steve > > > No, the telco network is 8 bits, 8000 times each second.No, the telco network is 12 bits, compressed to 8 bits in a pseudo logarithmic manner. Its dynamic range is 12 bits. Steve
ping: Jim Thompson
Started by ●April 24, 2006
Reply by ●April 25, 20062006-04-25
Reply by ●April 25, 20062006-04-25
Hello Steve,>> >> Zero-crossers are pretty much a thing of the past here, just like they >> are for medical ultrasound Doppler. You can do it in the digital >> domain these days. All it takes is a good uC such as the MSP430. But >> not a version with a puny 10 or 12 bit converter. They offer some that >> convert to 16 bits. > > What's wrong with a 12 bit converter? The entire telephone network uses > 12 bits. >Nothing wrong with it. But on a noisy channel that contains some radio links it might not cut it. Why settle for 12bits when you can buy a uC with a 16bit converter at around the same budget? It's not advertised much for some reason but the MSP430F2013 contains a 16bitter and can be had between $1.50 and $2.00 depending on volume. I believe its prime market is power metering and that probably doesn't require much advertising. Regards, Joerg http://www.analogconsultants.com
Reply by ●April 25, 20062006-04-25
Steve Underwood wrote:> Don Bowey wrote: > >> On 4/25/06 12:14 AM, in article e2ki8j$cuh$1@home.itg.ti.com, "Steve >> Underwood" <steveu@dis.org> wrote: >> >> >>> Joerg wrote: >>> >>>> Hello Jim, >>>> >>>> >>>>> 1200 baud FSK changes frequency in a _single_ cycle, so period-type >>>>> demodulation goes to crap quickly in the presence of noise. >>>>> >>>> >>>> Zero-crossers are pretty much a thing of the past here, just like they >>>> are for medical ultrasound Doppler. You can do it in the digital domain >>>> these days. All it takes is a good uC such as the MSP430. But not a >>>> version with a puny 10 or 12 bit converter. They offer some that >>>> convert >>>> to 16 bits. >>> >>> >>> What's wrong with a 12 bit converter? The entire telephone network uses >>> 12 bits. >>> >>> Steve >> >> >> >> No, the telco network is 8 bits, 8000 times each second. > > > No, the telco network is 12 bits, compressed to 8 bits in a pseudo > logarithmic manner. Its dynamic range is 12 bits. > > SteveNo, it's dynamic range is 48dB -- but only in the sense that you can listen to something, then the same thing 48dB down. You _can't_ listen to one signal at max amplitude at the same time you're hearing another one, undistorted, 48dB down. This is fun. I'm waiting for the response to this post that starts out "No, ..." -- Tim Wescott Wescott Design Services http://www.wescottdesign.com Posting from Google? See http://cfaj.freeshell.org/google/
Reply by ●April 25, 20062006-04-25
Tim Wescott wrote:> Steve Underwood wrote: > >> Don Bowey wrote: >> >>> On 4/25/06 12:14 AM, in article e2ki8j$cuh$1@home.itg.ti.com, "Steve >>> Underwood" <steveu@dis.org> wrote: >>> >>> >>>> Joerg wrote: >>>> >>>>> Hello Jim, >>>>> >>>>> >>>>>> 1200 baud FSK changes frequency in a _single_ cycle, so period-type >>>>>> demodulation goes to crap quickly in the presence of noise. >>>>>> >>>>> >>>>> Zero-crossers are pretty much a thing of the past here, just like they >>>>> are for medical ultrasound Doppler. You can do it in the digital >>>>> domain >>>>> these days. All it takes is a good uC such as the MSP430. But not a >>>>> version with a puny 10 or 12 bit converter. They offer some that >>>>> convert >>>>> to 16 bits. >>>> >>>> >>>> >>>> What's wrong with a 12 bit converter? The entire telephone network uses >>>> 12 bits. >>>> >>>> Steve >>> >>> >>> >>> >>> No, the telco network is 8 bits, 8000 times each second. >> >> >> >> No, the telco network is 12 bits, compressed to 8 bits in a pseudo >> logarithmic manner. Its dynamic range is 12 bits. >> >> Steve > > > No, it's dynamic range is 48dB -- but only in the sense that you can > listen to something, then the same thing 48dB down. You _can't_ listen > to one signal at max amplitude at the same time you're hearing another > one, undistorted, 48dB down. > > This is fun. I'm waiting for the response to this post that starts out > "No, ..."No, [ :-) ], you can't ordinarily do that anyway. Masking. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●April 25, 20062006-04-25
On 4/25/06 9:49 AM, in article erudncGPy7ioztPZRVn-gQ@rcn.net, "Jerry Avins" <jya@ieee.org> wrote:> Don Bowey wrote: >> On 4/25/06 12:14 AM, in article e2ki8j$cuh$1@home.itg.ti.com, "Steve >> Underwood" <steveu@dis.org> wrote: >> >> >>> Joerg wrote: >>> >>>> Hello Jim, >>>> >>>> >>>>> 1200 baud FSK changes frequency in a _single_ cycle, so period-type >>>>> demodulation goes to crap quickly in the presence of noise. >>>>> >>>> >>>> Zero-crossers are pretty much a thing of the past here, just like they >>>> are for medical ultrasound Doppler. You can do it in the digital domain >>>> these days. All it takes is a good uC such as the MSP430. But not a >>>> version with a puny 10 or 12 bit converter. They offer some that convert >>>> to 16 bits. >>> >>> What's wrong with a 12 bit converter? The entire telephone network uses >>> 12 bits. >>> >>> Steve >> >> >> No, the telco network is 8 bits, 8000 times each second. > > The eight bits are derived via A-law or mu-law from 12-bit data. > > JerryOnly if the bits are being used to provide a voice channel, as contrasted to a 64 kbit/s digital channel or concatinated digital channels. Don
Reply by ●April 25, 20062006-04-25
Tim Wescott wrote:> Steve Underwood wrote: > >> Don Bowey wrote: >> >>> On 4/25/06 12:14 AM, in article e2ki8j$cuh$1@home.itg.ti.com, "Steve >>> Underwood" <steveu@dis.org> wrote: >>> >>> >>>> Joerg wrote: >>>> >>>>> Hello Jim, >>>>> >>>>> >>>>>> 1200 baud FSK changes frequency in a _single_ cycle, so period-type >>>>>> demodulation goes to crap quickly in the presence of noise. >>>>>> >>>>> >>>>> Zero-crossers are pretty much a thing of the past here, just like they >>>>> are for medical ultrasound Doppler. You can do it in the digital >>>>> domain >>>>> these days. All it takes is a good uC such as the MSP430. But not a >>>>> version with a puny 10 or 12 bit converter. They offer some that >>>>> convert >>>>> to 16 bits. >>>> >>>> >>>> What's wrong with a 12 bit converter? The entire telephone network uses >>>> 12 bits. >>>> >>>> Steve >>> >>> >>> >>> No, the telco network is 8 bits, 8000 times each second. >> >> >> No, the telco network is 12 bits, compressed to 8 bits in a pseudo >> logarithmic manner. Its dynamic range is 12 bits. >> >> Steve > > No, it's dynamic range is 48dB -- but only in the sense that you can > listen to something, then the same thing 48dB down. You _can't_ listen > to one signal at max amplitude at the same time you're hearing another > one, undistorted, 48dB down. > > This is fun. I'm waiting for the response to this post that starts out > "No, ..." >No. The SDR of u-law and a-law is a lot less than 48dB. It is more like 30dB. 48dB would be the range of an 8 bit number. The telephone network kinda has 5 bit numbers and 3 bit exponents. Steve
Reply by ●April 25, 20062006-04-25
On 4/25/06 9:56 AM, in article e2lkbv$nt2$1@nnews.pacific.net.hk, "Steve Underwood" <steveu@dis.org> wrote:> Don Bowey wrote: >> On 4/25/06 12:14 AM, in article e2ki8j$cuh$1@home.itg.ti.com, "Steve >> Underwood" <steveu@dis.org> wrote: >> >> >>> Joerg wrote: >>> >>>> Hello Jim, >>>> >>>> >>>>> 1200 baud FSK changes frequency in a _single_ cycle, so period-type >>>>> demodulation goes to crap quickly in the presence of noise. >>>>> >>>> >>>> Zero-crossers are pretty much a thing of the past here, just like they >>>> are for medical ultrasound Doppler. You can do it in the digital domain >>>> these days. All it takes is a good uC such as the MSP430. But not a >>>> version with a puny 10 or 12 bit converter. They offer some that convert >>>> to 16 bits. >>> >>> What's wrong with a 12 bit converter? The entire telephone network uses >>> 12 bits. >>> >>> Steve >> >> >> No, the telco network is 8 bits, 8000 times each second. > > No, the telco network is 12 bits, compressed to 8 bits in a pseudo > logarithmic manner. Its dynamic range is 12 bits. > > SteveLet me express this more technically........ You are terribly mistaken. However, program channels that are better than the C-message weighted ones, use bits from multiple channels to achieve a better response, but the numbers of these is miniscule compared to the message network. Could you possibly be thinking of a ADPCM application used in private networks? Don
Reply by ●April 26, 20062006-04-26
Don Bowey wrote:> On 4/25/06 9:49 AM, in article erudncGPy7ioztPZRVn-gQ@rcn.net, "Jerry Avins" > <jya@ieee.org> wrote: > > >>Don Bowey wrote: >> >>>On 4/25/06 12:14 AM, in article e2ki8j$cuh$1@home.itg.ti.com, "Steve >>>Underwood" <steveu@dis.org> wrote: >>> >>> >>> >>>>Joerg wrote: >>>> >>>> >>>>>Hello Jim, >>>>> >>>>> >>>>> >>>>>>1200 baud FSK changes frequency in a _single_ cycle, so period-type >>>>>>demodulation goes to crap quickly in the presence of noise. >>>>>> >>>>> >>>>>Zero-crossers are pretty much a thing of the past here, just like they >>>>>are for medical ultrasound Doppler. You can do it in the digital domain >>>>>these days. All it takes is a good uC such as the MSP430. But not a >>>>>version with a puny 10 or 12 bit converter. They offer some that convert >>>>>to 16 bits. >>>> >>>>What's wrong with a 12 bit converter? The entire telephone network uses >>>>12 bits. >>>> >>>>Steve >>> >>> >>>No, the telco network is 8 bits, 8000 times each second. >> >>The eight bits are derived via A-law or mu-law from 12-bit data. >> >>Jerry > > > Only if the bits are being used to provide a voice channel, as contrasted to > a 64 kbit/s digital channel or concatinated digital channels.When you send bits, you send bits. The converter used for sending voice has 12 bits. (It will have 8 outputs if the pseudo-log converter is integrated with it.) Jerry -- Dr. Bettelheim, when I knit, I knit; when I masturbate, I masturbate. -- Helen Krasnow, as a student at Barnard College. �����������������������������������������������������������������������
Reply by ●April 26, 20062006-04-26
Steve Underwood wrote:> Tim Wescott wrote: > >> Steve Underwood wrote: >> >>> Don Bowey wrote: >>> >>>> On 4/25/06 12:14 AM, in article e2ki8j$cuh$1@home.itg.ti.com, "Steve >>>> Underwood" <steveu@dis.org> wrote: >>>> >>>> >>>>> Joerg wrote: >>>>> >>>>>> Hello Jim, >>>>>> >>>>>> >>>>>>> 1200 baud FSK changes frequency in a _single_ cycle, so period-type >>>>>>> demodulation goes to crap quickly in the presence of noise. >>>>>>> >>>>>> >>>>>> Zero-crossers are pretty much a thing of the past here, just like >>>>>> they >>>>>> are for medical ultrasound Doppler. You can do it in the digital >>>>>> domain >>>>>> these days. All it takes is a good uC such as the MSP430. But not a >>>>>> version with a puny 10 or 12 bit converter. They offer some that >>>>>> convert >>>>>> to 16 bits. >>>>> >>>>> >>>>> >>>>> What's wrong with a 12 bit converter? The entire telephone network >>>>> uses >>>>> 12 bits. >>>>> >>>>> Steve >>>> >>>> >>>> >>>> >>>> No, the telco network is 8 bits, 8000 times each second. >>> >>> >>> >>> No, the telco network is 12 bits, compressed to 8 bits in a pseudo >>> logarithmic manner. Its dynamic range is 12 bits. >>> >>> Steve >> >> >> No, it's dynamic range is 48dB -- but only in the sense that you can >> listen to something, then the same thing 48dB down. You _can't_ >> listen to one signal at max amplitude at the same time you're hearing >> another one, undistorted, 48dB down. >> >> This is fun. I'm waiting for the response to this post that starts >> out "No, ..." >> > No. The SDR of u-law and a-law is a lot less than 48dB. It is more like > 30dB. 48dB would be the range of an 8 bit number. The telephone network > kinda has 5 bit numbers and 3 bit exponents. > > SteveOh. Dangit. How'd I get 12 * 6 = 48? Must be the New Math. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com Posting from Google? See http://cfaj.freeshell.org/google/
Reply by ●April 26, 20062006-04-26
Tim Wescott wrote:> Steve Underwood wrote: >> Tim Wescott wrote: >> >>> Steve Underwood wrote: >>> >>>> Don Bowey wrote: >>>> >>>>> On 4/25/06 12:14 AM, in article e2ki8j$cuh$1@home.itg.ti.com, "Steve >>>>> Underwood" <steveu@dis.org> wrote: >>>>> >>>>> >>>>>> Joerg wrote: >>>>>> >>>>>>> Hello Jim, >>>>>>> >>>>>>> >>>>>>>> 1200 baud FSK changes frequency in a _single_ cycle, so period-type >>>>>>>> demodulation goes to crap quickly in the presence of noise. >>>>>>>> >>>>>>> >>>>>>> Zero-crossers are pretty much a thing of the past here, just like >>>>>>> they >>>>>>> are for medical ultrasound Doppler. You can do it in the digital >>>>>>> domain >>>>>>> these days. All it takes is a good uC such as the MSP430. But not a >>>>>>> version with a puny 10 or 12 bit converter. They offer some that >>>>>>> convert >>>>>>> to 16 bits. >>>>>> >>>>>> >>>>>> >>>>>> What's wrong with a 12 bit converter? The entire telephone network >>>>>> uses >>>>>> 12 bits. >>>>>> >>>>>> Steve >>>>> >>>>> >>>>> >>>>> >>>>> No, the telco network is 8 bits, 8000 times each second. >>>> >>>> >>>> >>>> No, the telco network is 12 bits, compressed to 8 bits in a pseudo >>>> logarithmic manner. Its dynamic range is 12 bits. >>>> >>>> Steve >>> >>> >>> No, it's dynamic range is 48dB -- but only in the sense that you can >>> listen to something, then the same thing 48dB down. You _can't_ >>> listen to one signal at max amplitude at the same time you're hearing >>> another one, undistorted, 48dB down. >>> >>> This is fun. I'm waiting for the response to this post that starts >>> out "No, ..." >>> >> No. The SDR of u-law and a-law is a lot less than 48dB. It is more >> like 30dB. 48dB would be the range of an 8 bit number. The telephone >> network kinda has 5 bit numbers and 3 bit exponents. >> >> Steve > > Oh. Dangit. How'd I get 12 * 6 = 48? Must be the New Math. >"Forty-eight? How did forty-eight get into it?" I hear you cry. Well, forty-eight is 6*8, don't you see? (Well, you ask a silly question, and you get a silly answer.) Apologies to Tom Lehrer :-) Steve
